• 소음진동
• /
• 제9권5호
• /
• pp.949-954
• /
• 1999

Speed-up and mass reduction of railway vehicle usually causes increased of the interior noise. One of the best ways to control the interior noise is to identify the noise level radiated from each of parts in the cabin. In this paper, we describe the method to estimate the interior noise nad evaluate the noise contribution to each of parts. This method is based that the sound pressure can be calculated by using the frequency response function and acceleration. According to analysis of the noise contribution, we validated that the noise radiated from the floor is the higher in the cabin. We also measured the noise distribution for the side and floor by using the microphone array in order to analyze the effect of the noise flowing into the cabin from the outdoors. Finally, we presented the plan of the interior noise reduction based on the noise levels radiated from each of parts.

• International Journal of Automotive Technology
• /
• 제8권3호
• /
• pp.309-317
• /
• 2007

In this study, we conducted a vibration fatigue analysis of the lower control arm in a vehicle suspension system. The vehicle was driven during the tests so that the dynamic effects could be taken into account. The dynamic load of the frequency domain was superimposed on the frequency response analysis. We performed a virtual proving ground test using multi-body dynamics, along with a finite element analysis and fatigue life predictions. Shape optimization was also considered using the design of the experimental approach, and a response surface analysis was performed to improve the durability performance of the lower control arm. We identified the elements that had the most influence on the optimal shape of the finite element model and analyzed the sensitivity of those elements. Then the optimal points that minimized the amount of damage to the areas of interest were determined through a response surface analysis. The results suggested that the fatigue life of the model increased as its mass was not increased excessively, and demonstrated that these design procedures yielded an appropriate optimized lower control arm model.

• 대한기계학회논문집A
• /
• 제41권8호
• /
• pp.711-719
• /
• 2017

날개 없는 선풍기는 특유의 형태로 인한 안전성과 청소의 간편함, 심미성으로 제품화에 성공하였다. 그러나 기존 선풍기에 비해 약한 바람과 모터에 의한 소음과 같은 단점은 구매력을 감소시키는 주요인이며, 따라서 모터의 속도를 증가시키지 않고 바람의 세기를 증가시키는 방안이 필요하다. 본 연구에서는 질량유량에 영향을 주는 인자, 수준을 선정하고 이를 실험계획법인 직교배열표를 이용하여 실험점을 배치하였다. 질량유량의 값은 전산유체해석 프로그램인 ANSYS FLUENT를 사용하여 질량유량의 값을 확인하였으며, 평균분석을 통해 질량유량에 가장 큰 영향을 주는 인자는 노즐 간격임을 확인할 수 있었다. 또한 예측 모델 식을 통해 얻은 질량유량의 값과 전산유체해석의 질량유량의 값이 가장 큰 값으로 일치하는 것을 나타내었다. 본 연구를 통해서 모터의 속도를 증가시키지 않더라도 형상 변화를 통해 질량유량의 증가시킴을 확인할 수 있었다.

• Natural Product Sciences
• /
• 제24권3호
• /
• pp.206-212
• /
• 2018

Xanthii Fructus has been traditionally used for the treatment of rhinitis, rheumatoid arthritis, and eczema. In this study, a high-performance liquid chromatography-photodiode array (HPLC-PDA) method was developed and then used for the simultaneous analysis of eight phenylpropanoids in Xanthii Fructus. The analytical column used for this separation was a $SunFire^{TM}$ $C_{18}$ column, maintained at $40^{\circ}C$. The mobile phase used was 1.0% acetic acid in distilled water and 1.0% acetic acid in acetonitrile with gradient elution. For identify of each component, the mass spectrometer (MS) was used a Waters triple quadrupole mass spectrometer requipped with electrospray ionization (ESI) source. The HPLC-PDA method showed good linearity: correlation coefficients were ${\geq}0.9996$. The limits of detection and quantification of the eight compounds were 0.02 - 0.04 and $0.06-0.14{\mu}g/mL$, respectively. The extraction recoveries ranged from 97.51 to 108.67%. The relative standard deviation values of intra- and inter-day precision were 0.06 - 1.55 and 0.09 - 1.68%, respectively. The validated HPLC-PDA method was applied to simultaneously analyse the amounts of eight phenlypropanoids in Xanthii Fructus.

• Journal of Ginseng Research
• /
• 제40권4호
• /
• pp.382-394
• /
• 2016

Background: Ginsenosides are the characteristic and principal components which manifest a variety of the biological and pharmacological activities of the roots and rhizomes of Panax ginseng (GRR). This study was carried out to qualitatively and quantitatively determine the ginsenosides in the cultivated and forest GRR. Methods: A rapid and sensitive ultra-high-performance liquid chromatography coupled with diode-array detector and quadrupole/time of flight tandem mass spectrometry (UPLC-DAD-QTOF-MS/MS) was applied to the qualitative analysis of ginsenosides and a 4000 QTRAP triple quadrupole tandem mass spectrometer (HPLC-ESI-MS) was applied to quantitative analysis of 19 ginsenosides. Results: In the qualitative analysis, all ingredients were separated in 10 min. A total of 131 ginsenosides were detected in cultivated and forest GRR. The method for the quantitative determination was validated for linearity, precision, and limits of detection and quantification. 19 representative ginsenosides were quantitated. The total content of all 19 ginsenosides in the forest GRR were much higher than those in the cultivated GRR, and were increased with the growing ages. Conclusion: This newly developed analysis method could be applied to the quality assessment of GRR as well as the distinction between cultivated and forest GRR.

• 한국생산제조학회지
• /
• 제24권3호
• /
• pp.308-313
• /
• 2015

In this research, a multi-objective optimal design of a scroll compressor lower frame was approximated, and the design parameters of the lower frame were selected. The sensitivity of the design parameters was induced through a parameter analysis, and the thickness was determined to be the most sensitive parameter to stress and deflection. All of the design parameters regarding the mass are sensitive factors. It was formulated for the problem about stress and deflection to be caused by the axial load. The sensitivity of the design variables was determined using an orthogonal array for the parameter analysis. Using the central composite and D-optimal designs, a second polynomial approximation of the objective and constraint functions was formulated and the accuracy was verified through an R-square. These functions were applied to the optimal design program (NSGA-II). Through a CAE analysis, the effectiveness of the central composite and D-optimal designs was determined.

• 한국생산제조학회지
• /
• 제24권4호
• /
• pp.407-413
• /
• 2015

Research for renewable energy is being performed since it has the merits of little pollution of the environment and sustainable energy resources. Microalgae is attractive as a renewable energy resource. Biomass of the microalgae can be produced by mass culturing, and bulk harvest technology of is needed to produce biomass continuously. Recently, ultrasonic waves were used to harvest the cultivated microalgae continuously. In this study, the separation process using ultrasonic waves was performed to effectively harvest the microalgae. An ultrasonic wave separation resonator was designed and manufactured based on the acoustic field analysis. Separation experiments using design of experiment were carried out, and the influence of experimental variables from the ultrasonic wave separation process was investigated. Mixing conditions of variables were estimated to obtain high separation efficiency and a large microalgae harvest. Experimental results for suitable mixing conditions were compared with simulation results calculated from the state equation.

• Journal of Power Electronics
• /
• 제12권3호
• /
• pp.487-494
• /
• 2012

A new low cost high power density photovoltaic power conditioning system (PV PCS) with an energy storage system is proposed in this paper. Its high power density and cost effectiveness can be achieved through the unification of the maximum power point tracker and the battery charger/discharger. Despite the reduced power stage, the proposed system can achieve the same performance in terms of maximum power point tracking and battery charging/discharging as the conventional system. When a utility power failure happens, the proposed system cannot perform maximum power point tracking at the UPS mode. However, the predetermined battery voltage near the maximum power point of the PV array can effectively generate a reasonable PV power even at the UPS mode. Therefore, it features a simpler structure, less mass, lower cost, and fewer devices. Finally, to confirm the operation, validity, and features of the proposed system, a theoretical analysis and experimental results from a single phase AC 220Vrms/1.5kW prototype are presented.

• 대한안전경영과학회지
• /
• 제2권3호
• /
• pp.27-36
• /
• 2000

The Robust Design method uses a mathematical tool called orthogonal arrays to study a large number of decision variables with a small number of experiments. It also uses a new measure of quality, called signal-to-noise (S/N) ratio, to predict the quality from the customer's perspective. Thus, the most economical product and process design from both manufacturing and customers' viewpoints can be accomplished at the smallest, affordable development cost. Many companies, big and small, high-tech and low-tech, have found the Robust Design method valuable in making high-quality products available to customers at a low competitive price while still maintaining an acceptable profit margin. A study to analyze and solve problems of a biochemical process experiment has presented in this paper. We have taken Taguchi's parameter design approach, specifically orthogonal array, and determined the optimal levels of the selected variables through analysis of the experimental results using S/N ratio.

• 지질공학
• /
• 제18권3호
• /
• pp.287-295
• /
• 2008

암반사면은 다수의 불규칙한 패턴의 불연속면들이 내재되어 있는 불연속체로써 암반 내에 존재하는 절리는 암반의 수리적, 역학적 거동을 좌우하는 중요한 요소이다. 이러한 절리들의 수리적, 역학적인 특성은 각각 다르게 나타날 수 있으며, 이러한 특성은 사면 설계에 중요한 요소이다. 다수의 절리패턴을 가진 암반의 구조적 특성을 사면안정해석과 물리탐사 결과로부터 분석하여 지반의 구조적 문제점을 분석하였다. 본 연구지역은 5개 구간을 설정하여 총 5개 측선에 대해 전기비저항 쌍극자탐사를 실시하였으며, 20개 사면에 대해 SWEDCE 및 SLIDE 프로그램을 이용해 사면 안정성 해석을 함께 수행하였다.